两种技术路线的重型车整车载荷对排放的影响研究

发布时间：2018-01-09 02:02

本文关键词：两种技术路线的重型车整车载荷对排放的影响研究　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文以两辆符合国Ⅵ排放水平的重型车整车为研究对象,开展国Ⅵ重型车整车排放实验研究。实验在重型底盘测功机上进行,选取0%、25%、50%、75%和100%整车载荷为不同工况点,运行C-WTVC循环。两辆样车分别采用DOC+SCR+DPF+EGR和DOC+SCR+DPF的后处理技术路线,实验前首先对两辆样车进行重复性排放验证,确定两辆样车的数据一致性与工况跟踪性是否符合实验要求,并对两辆样车进行不同载荷下的阻力参数分析。将氮氧分析仪与CVS全流稀释采样系统的采样设备并联安装,构建了符合本研究要求的实验系统。实验获得了不同整车载荷工况下的NOx、HC、CO等气体污染物的排放数据,测量了整车颗粒物质量及数量排放情况,利用氮氧分析仪对NOx排放进行了细化分析并对NH3的排放进行了测量,同时采集了排气温度、NOx原机排放、EGR流量等车辆基本运行参数。通过数据处理,分析了国Ⅵ重型车在不同载荷工况下NOx和颗粒物的排放规律,以及NOx主要组成成分NO、NO2和N2O的排放规律。探讨了车辆气体和颗粒污染物排放受载荷变化的影响,以及不同技术路线车辆排放受载荷影响差异性。全文工作内容及所得的主要结论概括如下:(1)通过两辆样车的气体污染物排放受载荷变化的影响研究发现,对于达到国Ⅵ排放标准的重型车整车,两种后处理技术路线重型车的HC和CO排放均不受载荷影响。未采用EGR技术的车辆,其NOx排放会随着载荷的增大而降低;采用EGR技术的车辆,NOx排放会随着载荷的增大先升高后降低。(2)通过对NOx排放规律研究发现,在C-WTVC循环实验中,两种技术路线的重型车,其NOx排放均主要由循环起始前半段提供。在循环前500~800s,NOx排放占整个循环的80%以上,且这一比例会随着载荷的增大而增加。载荷通过影响排气温度,改变后处理SCR催化器工作时间点来影响排放。采用不同技术路线车辆的排气温度受载荷影响不同,采用EGR技术的车辆其排温上升快,但排气温度随载荷变化的波动范围小;未采用EGR技术的车辆其排温上升慢,但排气温度随载荷变化的波动范围大。综合来看,未采用EGR技术的车辆,其NOx排放对载荷变化的影响比较敏感,较易受到载荷变化的影响;采用EGR技术的车辆,其NOx排放受载荷变化影响相对较小。(3)通过对NOx原机排放研究发现,在同载荷工况下,NOx原机排放对后NOx的排放影响较大。在循环起始前几百秒,SCR催化器未开始高效转化,此时原机排放水平将直接影响整个循环的排放水平。未采用EGR技术的车辆,其NOx原机排放随着载荷的增大而升高;采用EGR技术的车辆,其NOx原机排放随着载荷的增大先升高后保持平稳。在不同载荷工况下,两技术路线的车辆,其NOx排放均主要受排气温度变化的影响,不受NOx原机排放随载荷变化趋势的影响。(4)对NOx进一步分析,以及对NO、NO2和N2O的排放规律进行研究发现,两种技术路线的重型车,NOx各组成成分的排放最大值均会随着载荷的增大而升高,随着载荷的增大更容易出现极端排放情况。对于未采用EGR技术的国Ⅵ重型车,其N2O排放量较低,N02排放略高;NO、NO2和N2O的排放都会随着载荷的升高而降低,三者都主要生成于循环的前半段,与NOx总量的排放趋势一致。采用EGR技术的国Ⅵ重型车,其N2O排放量较高,NO2排放量极低,且N2O的排放趋势与EGR流量具有对应一致关系。其中NO和NO2主要产生于循环的前半段,N2O主要产生于循环的后半段。(5)通过对颗粒物排放规律和受载荷变化影响研究发现,未采用EGR技术的车辆其颗粒物排放主要集中在C-WTVC循环开始和末尾位置;采用EGR技术的车辆,其颗粒物排放由整个循环提供。相对于未采用EGR技术的车辆,其颗粒物排放极端情况较少,在整个循环内呈平稳波动状态,颗粒物排放值范围较小,排放比较稳定,受车辆行驶工况影响较小。未采用EGR技术的车辆,其颗粒物排放随着整车载荷的变化呈逐渐下降趋势。采用EGR技术的车辆,其颗粒物排放随着增和的增加先降低后升高。究其原因,低载荷时,少量的EGR流量会使燃烧持续期变长,延长颗粒物的氧化时间。随着整车载荷的增加,EGR流量逐渐增加,会导致气缸内氧含量减少,燃烧情况变差,降低缸内温度,从而降低颗粒物的氧化速率。
[Abstract]:In this paper, two vehicles comply with the level of the heavy vehicle emission as the research object, research on vehicle emission experiment in heavy vehicles. In experiment VI heavy chassis dynamometer, select 0%, 25%, 50%, 75% and 100% of vehicle load for different operating points, running C-WTVC. Two prototypes were used to DOC+SCR+DPF+EGR DOC+SCR+DPF and postprocessing techniques, the experiment before the first of two prototypes of repetitive discharge verification, determine the two prototypes of the data consistency and condition tracking whether meet the requirements, and the two cars were analyzed under different load resistance parameters. The nitrogen oxygen analyzer and CVS full flow dilution sampling system sampling equipment installed in parallel, built in line with the experimental requirements of the system. The experiment obtains different vehicle load conditions NOx, HC, CO and other gas pollutant emissions data, vehicle particulate matter measurement The amount and quantity of emissions, emissions of NOx and makes a detailed analysis on the NH3 emissions were measured by nitrogen oxygen analyzer, collected at the same time the exhaust gas temperature, NOx engine emissions, the basic operation parameters of EGR traffic vehicles. Through data processing, analysis of the emissions of heavy vehicles in China VI different load conditions NOx and the particles, as well as NOx main component of NO, emission of NO2 and N2O. To investigate the effect of vehicle gas and particle emission by the change of load, and the different technical route of vehicle emission load effect difference. The main conclusions and the contents are summarized as follows: (1) the effect of gas two vehicle emission load changes, to reach the discharge standard of heavy vehicle VI, two kinds of postprocessing technique route of heavy-duty vehicle HC and CO emissions were not affected by the load impact. Without using the EG R technology of the vehicle, the NOx emission will decrease with the increase of load; using the technology of EGR vehicles, NOx emissions with the increase of the load is increased first and then decreased. (2) through the research of emission of NOx found in the C-WTVC cycle experiment, heavy truck two techniques, the NOx emissions were mainly by the first half cycle starting. 500~800s in circulation, NOx emissions accounted for more than 80% of the whole cycle, and this ratio will increase with the increase of load. The load through the influence of exhaust gas temperature, SCR catalytic converter working time points after changing to influence emissions. Using different technical route of the vehicle exhaust temperature load effect of different, using EGR technology the vehicle exhaust temperature rising fast, but the exhaust temperature fluctuation range with the change of load; EGR technology with its vehicle exhaust temperature rises slowly, but the exhaust temperature fluctuation range with load change. To comprehensive See, EGR did not use the vehicle, the NOx emissions impact on the change of load sensitive effects are more susceptible to the load change; using EGR technology of the vehicle, the NOx emission load change is relatively small. (3) found through the study of NOx engine emissions at the same loading condition, the original NOx the effects of NOx emissions after the engine emissions greatly. In the cycle before the initiation of hundreds of seconds, SCR catalyst has not started high transformation at this time of the original engine emission level will directly affect the entire cycle of emission levels. EGR technology is not used in the original diesel vehicles, NOx increased with the increase of the load; using the technology of EGR vehicles the original NOx engine emission with the increase of the load increased first and then remained stable. Under different load conditions, the two technical route of the vehicle, the NOx emissions were mainly affected by the variation of the exhaust temperature, not by NOx original diesel effect changing with the load (4) of the trend. NOx further analysis, as well as the NO, found that the emission of NO2 and N2O, two kinds of technology of heavy vehicle emissions, maximum value of the components of NOx are increased with the increase of the load, with the increase of the load more prone to extreme emissions. For not using EGR technology in heavy VI the car, the lower N2O emissions, N02 emissions slightly higher; NO, NO2 and N2O emissions will be reduced as the load increases, the three are mainly generated in the first half of the cycle, consistent with the trend of the total NOx emissions. Using EGR technology of VI heavy vehicles, the higher N2O emissions NO2, extremely low emissions, emission trends and EGR flow and N2O is corresponding to the consistent relationship. The main NO and NO2 produced in the first half of the cycle, N2O is mainly produced in the second half cycle. (5) by the law of the emissions of particulate matter and the effect of load change, not by EGR The vehicle the particulate emission is mainly concentrated in the C-WTVC loop start and end position; using EGR technology of the vehicle, the particulate emission provided by the whole cycle. Compared with EGR technology without the use of the vehicle, the less extreme particulate emissions, a steady state in the whole cycle fluctuations within the range of small particle emissions emissions, is relatively stable, the vehicle driving conditions affected. EGR technology is not used in the vehicle, the particulate emission change with the vehicle load decreased gradually. The EGR technology of the vehicle, the particulate emission increases with increasing and decreased firstly and then increased. The reason of low load, a small amount of EGR traffic the combustion duration becomes longer, the oxidation time of particles. With the increase of vehicle load, EGR traffic has increased, will lead to a reduction in the oxygen content of the cylinder combustion variation, reduce the temperature in cylinder, Thus the oxidation rate of particles is reduced.

【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X734.2;U467.48

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